1. Field of the Invention
The present invention relates to an apparatus for cleaning a magnetic head of a tape drive, and more particularly to a magnetic head which oscillates within an available actuator movement against a stationary brush for cleaning an air bearing surface of the magnetic bead.
2. Discussion of the Related Art
A magnetic tape drive employs a drive assembly which moves a magnetic tape across the air bearing surface of a magnetic head assembly for performing recording, playback and servo operations. In a typical tape drive the movement of the tape develops an air cushion between the tape and an air bearing surface of the head assembly which causes the tape to be spaced from the air bearing surface a small distance, this distance being referred to as the "flying height". Some head assemblies are provided with cross slots which extend perpendicular to the path of the tape for bleeding some of the air and reducing the flying height. The reason for this is because the lower the flying height the greater the signal which allows greater recording densities. Lateral positioning of the magnetic tape relative to the head assembly is typically implemented by a tape guide on each side of the head assembly.
The head assembly is provided with at least one of each of a write head, read head and a servo head. The servo head cooperates with servo processing circuitry to position a write head and/or read head with respect to a track on the magnetic tape. After receiving servo information from a servo track, the servo processing circuitry sends signals to an actuator which supports the magnetic head assembly. The actuator then moves the head assembly perpendicular to the path of the tape so that accurate positioning of the head assembly relative to the desired data track is achieved. In some tape drives the range of perpendicular motion of the head assembly can be relatively large.
A serious problem in magnetic tape drives is the tape debris that is accumulated on the air bearing surface of the head assembly. Most of this debris is generated by friction between the top edge of the tape and the aforementioned tape guides. This tape debris rains down on the air bearing surface and can produce poor performance of the tape drive. If the debris adheres to a read or write head, permanent data errors can occur. Further, the debris can clog up the cross slots, causing improper bleeding of air at the air bearing surface and unintended alteration of the flying height. Sometimes the debris is released from the cross slots in large chunks, which can cause momentary signal drop outs and temporary data errors.
Another serious problem in magnetic tape drives results from electrostatic discharge (ESD). As the tape flies past the head assembly a charge is built up on the head assembly which, if too great, can result in permanent damage to the sensitive elements of the head assembly. Since the build up of the charge is cumulative, the more the tape drive is used, the greater the charge. If this charge can be relieved before reaching an unacceptably high level, the sensitive elements can be protected. ESD can occur during maintenance of the head assembly or when touched by an operator.
A typical, commercially available magnetic tape drive is the 3590 tape drive made by International Business Machines (IBM). This drive has the components mentioned hereinabove. The 3590 tape drive employs a pantocam arm which carries a leader pin for capturing a leader block, the leader block being attached to the magnetic tape to be processed. After capturing the leader block the pantocam arm swings the leader block around an arcuate tape guide and then lodges the leader block in a reel. When the reel is rotated the tape moves adjacent the magnetic head, the magnetic head being located intermediate the tape guide. After the tape is processed, a reel in the cartridge returns the tape to the cartridge and the pantocam arm delivers the leader block to the cartridge, where it is released. The head assembly may now have collected some debris and accumulated a slight charge. It would be desirable if the head assembly could be cleaned and cleared of charge after processing each tape without adding to the cost and complexity of the drive.